Investigation of silicone rubber composites reinforced with carbon nanotube,nanographite, their hybrid,and applications for flexible devices

New technology is constantly required for updating new generation flexible devices, such as stretchable sensors, flexible electronics, and actuators. In the present study, a stretchable strain sensor, and actuator were developed based on room-temperature-vulcanized (RTV) silicone rubber reinforced with carbon nanotubes (CNTs), nanographite (GR), and CNT-GR hybrids. A CNT-based strain sensor developed for RTV silicone rubber showed improved stiffness and brittleness. For example, at 5 phr of filler loading, the compressive and tensile modulus for the CNT-reinforced RTV silicone matrix improved by 287% and 240%, respectively. Similarly, the improvements in the compressive and tensile modulus were moderate for the CNT-GR hybrid (210% and 235%) and low for GR (135% and 125%). The improved brittleness resulted in a higher fracture strain of 170% and 155% for the CNT-GR hybrid and GR, respectively. The improved mechanical properties were tested in real-life applications of actuation. The actuation displacement at a filler loading of 2 phr increased to 1.65 mm (CNT), 1.25 mm (CNT-GR), and 0.08 mm (GR). From 2 to 8 kV, the actuation displacement increased by 825% (CNT), 830% (CNT-GR), and 32% (GR). The strain sensor showed a stretchability of >100% (CNT) and >100% (CNT-GR). In addition, the gauge factor was higher for the CNT-GR hybrid composites. The durability measurements showed that the change in resistance was negligible for up to 5000 cycles in both the CNT and CNT-GR rubber composites. A series of experiments confirmed that compared to the composite based on RTV silicone rubber and CNT, the CNT-GR hybrid showed a robust flexibility and stretchability as a piezo-resistive strain sensor and actuator.     

Microstructure and Properties of Spark Plasma Sintered Carbon Nanotube Reinforced Aluminum Matrix Composites

In this paper, spark plasma sintering (SPS) of multi‐walled carbon nanotube (CNT) reinforced aluminum matrix composites is reported. Ball milling of the Al‐CNT mixture with polyacrylic acid (PAA) dispersion agent followed by SPS resulted in uniform dispersion of CNTs in dense composite compacts. Significant improvement in microhardness, nanohardness, and compressive yield strength was observed with 2 wt% CNT reinforcement in aluminum matrix composites. The Al‐CNT composites further exhibited improved wear resistance and lower friction coefficient due to strengthening and self‐lubricating effects of CNTs.     

PVD制备TiAlSiN涂层的研究进展

概述了物理气相沉积(PVD)技术制备TiAlSiN涂层的研究现状及发展趋势,详细分析了Si元素的添加及Si与Al元素的含量对TiAlSiN涂层的微观结构、力学性能、高温抗氧化性和热稳定性的影响。解决PVD制备TiAlSiN涂层较低的膜基结合力和较大的残余应力等问题应是今后重点研究的方向。     

Phytic acid in Indian soybean: genotypic variability and influence of growing location

Phytic acid, the heat‐stable anti‐nutritional factor, was determined in 80 cultivars/strains of Indian soybean to identify genotypes that possess low concentrations of phytic acid. Variation of values of 28.6–46.4 g kg⁻¹ soy flour was observed. Information on the influence of growing locations with widely differing soil types on phytic acid content being scarce, phytic acid in the mature dry seeds of eight Indian soybean cultivars grown over four locations was evaluated. Variation in different varieties at different locations was 27.8–45.0 g kg⁻¹ soy flour. Averaged over eight genotypes, the maximum mean value for phytic acid was observed at Pantnagar and the minimum at Palampur. These differences in locational mean values for phytic acid can be explained on the basis of characteristics of the soils and environment. The higher mean value at Pantnagar may be attributed to higher soil organic phosphorus, nearly neutral pH and favorable temperature from flowering to maturity. However, the lower value observed at Palampur can be explained by the acidic nature of its soil, with lower maximum and minimum temperatures prevailing from flowering to maturity. Locational and genotypic × locational effects were found to be significant (p < 0.01). The results indicated that soil characteristics and soil environment play a significant role in the accumulation of phytic acid in soybean seeds. Copyright © 2005 Society of Chemical Industry     

Triple-Networked Hybrid Hydrogels Reinforced with Montmorillonite Clay and Graphene Nanoplatelets for Soft and Hard Tissue Regeneration

Hydrogel is a three-dimensional (3D) soft and highly hydrophilic, polymeric network that can swell in water and imbibe a high amount of water or biological fluids. Hydrogels have been used widely in various biomedical applications. Hydrogel may provide a fluidic tissue-like 3D microenvironment by maintaining the original network for tissue engineering. However, their low mechanical performances limit their broad applicability in various functional tissues. This property causes substantial challenges in designing and preparing strong hydrogel networks. Therefore, we report the triple-networked hybrid hydrogel network with enhanced mechanical properties by incorporating dual-crosslinking and nanofillers (e.g., montmorillonite (MMT), graphene nanoplatelets (GNPs)). In this study, we prepared hybrid hydrogels composed of polyacrylamide, poly (vinyl alcohol), sodium alginate, MMT, and MMT/GNPs through dynamic crosslinking. The freeze-dried hybrid hydrogels showed good 3D porous architecture. The results exhibited a magnificent porous structure, interconnected pore-network surface morphology, enhanced mechanical properties, and cellular activity of hybrid hydrogels.     

Stability Analysis of Parallel Fuzzy P ＋ Fuzzy I ＋ Fuzzy D Control Systems

The study presented in this paper is in continuation with the paper published by the authors on parallel fuzzy proportional plus fuzzy integral plus fuzzy derivative (FP + FI + FD) controller. It addresses the stability analysis of parallel FP + FI + FD controller. The famous"small gain theorem" is used to study the bounded-input and bounded-output (BIBO) stability of the fuzzy controller. Sufficient BIBO-stability conditions are developed for parallel FP + FI + FD controller. FP + FI + FD controller is derived from the conventional parallel proportional plus integral plus derivative (PID) controller. The parallel FP + FI + FD controller is actually a nonlinear controller with variable gains. It shows much better set-point tracking, disturbance rejection and noise suppression for nonlinear processes as compared to conventional PID controller.     

Evaluation of Legal Risks for E-Commerce in Construction

E-commerce is steadily becoming a reality in the construction industry. However, despite the increasing rate of utilization by owners and contractors alike, the legal implications of using e-commerce in construction have not been studied in depth. This paper fills this gap in literature. It identifies and analyzes the different types of legal risks involved in the use of e-commerce in construction. It also outlines the risk that contractors and professionals may face in their e-commerce implementations. A classification of e-commerce legal risks is also introduced. The legal risks discussed include agency, jurisdiction, contract formation, validity and errors, authentication, attribution, nonrepudiation, privacy, conflict of laws, and conflict between law and technology.     

BE-SONOS flash memory along with metal gate and high-k dielectrics in tunnel barrier and its impact on charge retention dynamics

We investigate the effect of a high-k dielectric in the tunnel layer to improve the erase speed-retention trade-off. Here, the proposed stack in the tunnel layer is AlLaO₃/HfAlO/SiO₂. These proposed materials possess low valence band offset with high permittivity to improve both the erase speed and retention time in barrier engineered silicon-oxide-nitride-oxide-silicon(BE-SONOS). In the proposed structure HfAlO and AlLaO₃ replace Si₃N₄ and the top SiO₂ layer in a conventional oxide/nitride/oxide(ONO) tunnel stack. Due to the lower conduction band offset(CBO) and high permittivity of the proposed material in the tunnel layer, it offers better program/erase(P/E) speed and retention time. In this work the gate length is also scaled down from 220 to 55 nm to observe the effect of high-k materials while scaling, for the same equivalent oxide thickness(EOT). We found that the scaling down of the gate length has a negligible impact on the memory window of the devices. Hence, various investigated tunnel oxide stacks possess a good memory window with a charge retained up to 87.4%(at room temperature) after a period of ten years. We also examine the use of a metal gate instead of a polysilicon gate, which shows improved P/E speed and retention time.     

Ligand‐Free Copper‐Manganese Spinel Oxide‐Catalyzed Tandem One‐Pot C–H Amidation and N‐Arylation of Benzylamines: A Facile Access to 2‐Arylquinazolin‐4(3H)‐ones

An efficient ligand‐free copper‐manganese (Cu‐Mn) spinel oxide‐catalyzed direct tandem C−H oxygenation and N‐arylation of benzylamines has been developed. The method has been utilized for the synthesis of medicinally important 2‐arylquinazolin‐4(3H)‐ones. Salient features of this method include recyclable catalyst, no ligand, excellent product yields, shorter reaction times and a broad substrate scope.